tools/idl_parser/idl_lexer.py

   1 #!/usr/bin/env python
   2 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
   3 # Use of this source code is governed by a BSD-style license that can be
   4 # found in the LICENSE file.
   5
   6 """ Lexer for PPAPI IDL
   7
   8 The lexer uses the PLY library to build a tokenizer which understands both
   9 WebIDL and Pepper tokens.
  10
  11 WebIDL, and WebIDL regular expressions can be found at:
  12    http://www.w3.org/TR/2012/CR-WebIDL-20120419/
  13 PLY can be found at:
  14    http://www.dabeaz.com/ply/
  15 """
  16
  17 import optparse
  18 import os.path
  19 import sys
  20
  21 #
  22 # Try to load the ply module, if not, then assume it is in the third_party
  23 # directory.
  24 #
  25 try:
  26   # Disable lint check which fails to find the ply module.
  27   # pylint: disable=F0401
  28   from ply import lex
  29 except:
  30   module_path, module_name = os.path.split(__file__)
  31   third_party = os.path.join(module_path, '..', '..', 'third_party')
  32   sys.path.append(third_party)
  33   # pylint: disable=F0401
  34   from ply import lex
  35
  36 #
  37 # IDL Lexer
  38 #
  39 class IDLLexer(object):
  40   # 'tokens' is a value required by lex which specifies the complete list
  41   # of valid token types.
  42   tokens = [
  43     # Data types
  44       'float',
  45       'integer',
  46       'string',
  47
  48     # Symbol and keywords types
  49       'COMMENT',
  50       'identifier',
  51
  52     # MultiChar operators
  53       'ELLIPSIS',
  54   ]
  55
  56   # 'keywords' is a map of string to token type.  All tokens matching
  57   # KEYWORD_OR_SYMBOL are matched against keywords dictionary, to determine
  58   # if the token is actually a keyword.
  59   keywords = {
  60     'any' : 'ANY',
  61     'attribute' : 'ATTRIBUTE',
  62     'boolean' : 'BOOLEAN',
  63     'byte' : 'BYTE',
  64     'callback' : 'CALLBACK',
  65     'const' : 'CONST',
  66     'creator' : 'CREATOR',
  67     'Date' : 'DATE',
  68     'deleter' : 'DELETER',
  69     'dictionary' : 'DICTIONARY',
  70     'DOMString' : 'DOMSTRING',
  71     'double' : 'DOUBLE',
  72     'enum'  : 'ENUM',
  73     'false' : 'FALSE',
  74     'float' : 'FLOAT',
  75     'exception' : 'EXCEPTION',
  76     'getter': 'GETTER',
  77     'implements' : 'IMPLEMENTS',
  78     'Infinity' : 'INFINITY',
  79     'inherit' : 'INHERIT',
  80     'interface' : 'INTERFACE',
  81     'legacycaller' : 'LEGACYCALLER',
  82     'long' : 'LONG',
  83     'Nan' : 'NAN',
  84     'null' : 'NULL',
  85     'object' : 'OBJECT',
  86     'octet' : 'OCTET',
  87     'optional' : 'OPTIONAL',
  88     'or' : 'OR',
  89     'partial'  : 'PARTIAL',
  90     'readonly' : 'READONLY',
  91     'sequence' : 'SEQUENCE',
  92     'setter': 'SETTER',
  93     'short' : 'SHORT',
  94     'static' : 'STATIC',
  95     'stringifier' : 'STRINGIFIER',
  96     'typedef' : 'TYPEDEF',
  97     'true' : 'TRUE',
  98     'unsigned' : 'UNSIGNED',
  99     'unrestricted' : 'UNRESTRICTED',
 100     'void' : 'VOID'
 101   }
 102
 103   # Token definitions
 104   #
 105   # Lex assumes any value or function in the form of 't_<TYPE>' represents a
 106   # regular expression where a match will emit a token of type <TYPE>.  In the
 107   # case of a function, the function is called when a match is made. These
 108   # definitions come from WebIDL.
 109   def t_ELLIPSIS(self, t):
 110     r'\.\.\.'
 111     return t
 112
 113   def t_float(self, t):
 114     r'-?(([0-9]+\.[0-9]*|[0-9]*\.[0-9]+)([Ee][+-]?[0-9]+)?|[0-9]+[Ee][+-]?[0-9]+)'
 115     return t
 116
 117   def t_integer(self, t):
 118     r'-?(0([0-7]*|[Xx][0-9A-Fa-f]+)|[1-9][0-9]*)'
 119     return t
 120
 121
 122   # A line ending '\n', we use this to increment the line number
 123   def t_LINE_END(self, t):
 124     r'\n+'
 125     self.AddLines(len(t.value))
 126
 127   # We do not process escapes in the IDL strings.  Strings are exclusively
 128   # used for attributes and enums, and not used as typical 'C' constants.
 129   def t_string(self, t):
 130     r'"[^"]*"'
 131     t.value = t.value[1:-1]
 132     self.AddLines(t.value.count('\n'))
 133     return t
 134
 135   # A C or C++ style comment:  /* xxx */ or //
 136   def t_COMMENT(self, t):
 137     r'(/\*(.|\n)*?\*/)|(//.*(\n[ \t]*//.*)*)'
 138     self.AddLines(t.value.count('\n'))
 139     return t
 140
 141   # A symbol or keyword.
 142   def t_KEYWORD_OR_SYMBOL(self, t):
 143     r'_?[A-Za-z][A-Za-z_0-9]*'
 144
 145     # All non-keywords are assumed to be symbols
 146     t.type = self.keywords.get(t.value, 'identifier')
 147
 148     # We strip leading underscores so that you can specify symbols with the same
 149     # value as a keywords (E.g. a dictionary named 'interface').
 150     if t.value[0] == '_':
 151       t.value = t.value[1:]
 152     return t
 153
 154   def t_ANY_error(self, t):
 155     msg = 'Unrecognized input'
 156     line = self.Lexer().lineno
 157
 158     # If that line has not been accounted for, then we must have hit
 159     # EoF, so compute the beginning of the line that caused the problem.
 160     if line >= len(self.index):
 161       # Find the offset in the line of the first word causing the issue
 162       word = t.value.split()[0]
 163       offs = self.lines[line - 1].find(word)
 164       # Add the computed line's starting position
 165       self.index.append(self.Lexer().lexpos - offs)
 166       msg = 'Unexpected EoF reached after'
 167
 168     pos = self.Lexer().lexpos - self.index[line]
 169     out = self.ErrorMessage(line, pos, msg)
 170     sys.stderr.write(out + '\n')
 171     self._lex_errors += 1
 172
 173
 174   def AddLines(self, count):
 175     # Set the lexer position for the beginning of the next line.  In the case
 176     # of multiple lines, tokens can not exist on any of the lines except the
 177     # last one, so the recorded value for previous lines are unused.  We still
 178     # fill the array however, to make sure the line count is correct.
 179     self.Lexer().lineno += count
 180     for _ in range(count):
 181       self.index.append(self.Lexer().lexpos)
 182
 183   def FileLineMsg(self, line, msg):
 184     # Generate a message containing the file and line number of a token.
 185     filename = self.Lexer().filename
 186     if filename:
 187       return "%s(%d) : %s" % (filename, line + 1, msg)
 188     return "<BuiltIn> : %s" % msg
 189
 190   def SourceLine(self, line, pos):
 191     # Create a source line marker
 192     caret = ' ' * pos + '^'
 193     # We decrement the line number since the array is 0 based while the
 194     # line numbers are 1 based.
 195     return "%s\n%s" % (self.lines[line - 1], caret)
 196
 197   def ErrorMessage(self, line, pos, msg):
 198     return "\n%s\n%s" % (
 199         self.FileLineMsg(line, msg),
 200         self.SourceLine(line, pos))
 201
 202 #
 203 # Tokenizer
 204 #
 205 # The token function returns the next token provided by IDLLexer for matching
 206 # against the leaf paterns.
 207 #
 208   def token(self):
 209     tok = self.Lexer().token()
 210     if tok:
 211       self.last = tok
 212     return tok
 213
 214
 215   def GetTokens(self):
 216     outlist = []
 217     while True:
 218       t = self.Lexer().token()
 219       if not t:
 220         break
 221       outlist.append(t)
 222     return outlist
 223
 224   def Tokenize(self, data, filename='__no_file__'):
 225     lexer = self.Lexer()
 226     lexer.lineno = 1
 227     lexer.filename = filename
 228     lexer.input(data)
 229     self.lines = data.split('\n')
 230
 231   def KnownTokens(self):
 232     return self.tokens
 233
 234   def Lexer(self):
 235     if not self._lexobj:
 236       self._lexobj = lex.lex(object=self, lextab=None, optimize=0)
 237     return self._lexobj
 238
 239   def _AddConstDefs(self):
 240     # 'literals' is a value expected by lex which specifies a list of valid
 241     # literal tokens, meaning the token type and token value are identical.
 242     self.literals = r'"*.(){}[],;:=+-/~|&^?<>'
 243     self.t_ignore = ' \t'
 244
 245   def _AddToken(self, token):
 246     if token in self.tokens:
 247       raise RuntimeError('Same token: ' + token)
 248     self.tokens.append(token)
 249
 250   def _AddTokens(self, tokens):
 251     for token in tokens:
 252       self._AddToken(token)
 253
 254   def _AddKeywords(self, keywords):
 255     for key in keywords:
 256       value = key.upper()
 257       self._AddToken(value)
 258       self.keywords[key] = value
 259
 260   def __init__(self):
 261     self.index = [0]
 262     self._lex_errors = 0
 263     self.linex = []
 264     self.filename = None
 265     self.keywords = {}
 266     self.tokens = []
 267     self._AddConstDefs()
 268     self._AddTokens(IDLLexer.tokens)
 269     self._AddKeywords(IDLLexer.keywords)
 270     self._lexobj = None
 271
 272 # If run by itself, attempt to build the lexer
 273 if __name__ == '__main__':
 274   lexer = IDLLexer()